In various known types of case, bag, trunk and the like, the shoulder strap for carrying is usually rigidly coupled to the body of the bag or case by means of spring clips or other equivalent devices, which can be locked manually by snap action. Generally, the spring clips are fixed to the bags, cases and the like by means of stitches, adhesive bonding, or other low-cost techniques which allow rapid execution.
However, these fixing techniques have limited effectiveness and reliability when the bag or case being considered is intended for particular technical and professional applications rather than for simply carrying ordinary items (for example, for carrying delicate and expensive instruments); in these special applications, it must in fact be ensured that the shoulder strap does not separate accidentally from the body of the case due to breakage of the seams, separation of the parts joined by adhesive bonding, or other similar unwelcome mishaps. For this reason, the technician or professional who uses the case must also be able to check at all times the state of the reliability of the fixing in order to avoid accidental separations.